Patent GB-1117685-A (GB)
Title: Siloxane greases
IPC: C10M169/00
Filed: 1966-03-09
Abstract: A grease comprises by weight (a) 100 parts of a siloxane liquid of the average general formula <FORM:1117685/C3/1> where R is a monovalent hydrocarbon (h.c.) or halo-h.c. radical, each containing not more than 7 C atoms, free from aliphatic unsaturation, at least 85% of the R radicals being methyl radicals and n has an average value of 1.95 to 2.1, the viscosity of (a) being from 20 to 15,000 cs. at 25 DEG C.; (b) 5 to 25 parts of powdered SiO2 having a surface area of at least 100 m2/g.; (c) 2 to 35% by wt. of (b) of a cyclic siloxane of the formula (R2SiO)3, where R is as above except that at least 50% of the R radicals are methyl radicals; and (d) 5 to 100% by wt. of (b) of a hydroxylated organopolysiloxane containing an average of 1.8 to 2.1 R radicals per Si atom and a Si-bonded -OH content of at least 2% by wt.  Preferably (c) is sym-trimethyltriphenylcyclotrisiloxane, and (d) is a liquid hydroxylated phenylmethylsiloxane, The greases can be made by simply mixing the ingredients together, preferably in the presence of 0.2 to 10 mol. per cent, calculated on the moles of (b) of (e) a catalyst selected from NH4OH, (NH4)2CO3, NH4X, <FORM:1117685/C3/2> and NR113, or any mixture thereof, where X is Cl or F, R1 is H, CH3-or C2H5-and R11 is H or a monovalent h.c. radical and, if desired, in the presence of a solvent.  Generally the silica (b) is first treated with ingredients (c), (d) and (e), conveniently by mixing ingredients (b) to (e) in a volatile solvent dispersion, e.g. toluene, diethyleneglycoldimethylether, octane or chlorobenzene, evaporating the solvent, and after a few hours or days, adding ingredient (a) thereto.  Examples describe the above preparation of the greases.ALSO:A grease comprises by wt. (a) 100 pts. of a siloxane liquid of the average general formula <FORM:1117685/C4-C5/1> where R is a monovalenthydro carbon (h.c.) or halo-h.c. radical each containing not more than 7 C atoms, free from aliphatic unsaturation, at least 85% of the R radicals being methyl radicals and n has an average value of 1.95 to 2.1, the viscosity of (a) being from 20 to 15,000 cs. at 25 DEG  C.; (b) 5 to 25 pots. of powdered SiO2 having a surface area of at least 100 m2/g.; (c) 2 to 35% by wt. of (b) of a cyclic siloxane of the formula (R2SiO)3, where R is as above except that at least 50% of the R radicals are methyl radicals; and (d) 5 to 100% by wt. of (b) of a hydroxylated organopolysiloxane containing an average of 1.8 to 2.1 R radicals per Si atom and a Si-bonded-OH content of at least 2% by wt.  Preferably (c) is sym.-trimethyltriphenyl-cyclotrisiloxane and (d) is a liquid hydroxylated phenylmethylsiloxane.  The greases can be made by simply mixing the ingredients together, preferably in the presence of 0.2 to 10 mol. per cent, calculated on the moles of (b) of (e) a catalyst selected from NH4OH, (NH4)2CO3, <FORM:1117685/C4-C5/2> or any mixture thereof, where X is Cl or F, R1i s H, CH3- or C2H5-and R11 is H or a mono valent h.c. radical, and, if desired, in the presence of a solvent.  Generally the silica (b) is first treated with ingredients (c), (d) and (e), conveniently by mixing ingredients (b) to (e) in a volatile solvent dispersion, e.g. toluene, diethyleneglycoldimethylether, octane or chlorobenzene, evaporating the solvent, and after a few hours or days, adding ingredient (a) thereto.  Examples describe the above preparation of the greases.ALSO:Powdered silica, having a surface area of at least 100 m.2/g., is rendered hydrophobic by treatment with (a) 2 to 35% by wt. of the silica of a cyclic siloxane of the formula (R2SiO)3, where R is a monovalent hydrocarbon (h.c.) or halo-h.c. radical of not more than 7 C atoms and free of aliphatic unsaturation, at least 50% of the radicals being methyl radicals, (b) 50 to 100% by wt. of the silica of a hydroxylated organo-polysiloxane containing an average of 1.8 to 2.1 R radicals per Si atom and a Si-bonded-OH content of at least 2% by wt., and (c) a catalyst, which is NH4OH, (NH4)2CO3, <FORM:1117685/C1/1> or any mixture thereof, where X is Cl or F, R1 is H, CH3- or C2H5-, and R11 is H or a monovalent h.c. radicle, and, if desired in the presence, of a solvent.  Generally the above ingredients are mixed together in a solvent dispersion, e.g. toluene, diethylene-glycoldimethylether, octane or chlorobenzene, and the solvent is then evaporated off.